Oil prices have tumbled more than 20 percent his year, marking its worst performance for the first six months of the year since 1997.

Energy Aspect's Chief Oil Analyst, Amrita Sen, argued that while she would not dare predict the level at which oil prices could stabilize, she refused to rule out the possibility that prices could slip below $40 a barrel in the short-term.

Oil prices could be poised to fall below $40 a barrel before too long, according to an analyst at Energy Aspects, as the commodity appeared set to post its largest price slide in the first half of the year for the past two decades.

"This is like a falling knife right now, I genuinely haven't seen sentiment this bad ever," Amrita Sen, the co-founder and chief oil analyst at Energy Aspects, told CNBC on Wednesday.

"We have had clients emailing saying they have been trading this for 20 or 30 years and they have never seen something like this," she added.

Oil prices have tumbled more than 20 percent his year, marking its worst performance for the first six months of the year since 1997 and putting the commodity in bear market territory.

The ongoing decline in prices appears to have stemmed from investors discounting evidence of robust compliance by OPEC and non-OPEC producers with a deal to curtail a global supply overhang.

Prices took a fresh leg lower in the previous session – dipping 2 percent – as new signs of rising output from Nigeria and Libya, the two OPEC members exempt from a deal to cut production.

Output from the 14-member exporter group ticked higher in May due to rising production in Nigeria, Libya and Iraq, raising concerns about OPEC's effort to shrink global stockpiles of crude oil. OPEC and other producers have committed to keeping 1.8 million barrels a day off the market through March.

Libya's oil production rose more than 50,000 barrels per day to 885,000 bpd, a Libyan source told Reuters. Meanwhile, exports of Nigeria's benchmark Bonny Light crude oil are set to rise by 62,000 barrels per day in August, Reuters reported.

Sen argued that while she would not dare predict the level at which oil prices could stabilize, she refused to rule out the possibility that prices could slip below $40 a barrel in the short-term.

Brent crude traded $46.16 a barrel in early-afternoon deals on Wednesday, up 0.28 percent, while U.S. WTI crude was around $43.70 a barrel, up 0.44 percent.